Effect of Eucalyptus camaldulensis, Acacia salicina and Dalbergia sissoo plantation on soil

Populus euphratica Oliv. forests in river floodplains of Khuzestan province are degraded heavily. Tree plantation is one of the methods for restoration of these degraded sites. The plantations of Eucalyptus camaldulensis, Acacia salicina and Dalbergia sissoo were established in randomized complete block design in 1993 with three replications along Dez river. Soil macrofauna were collected by hand sorting, using two randomly located 0.25m2 sampling frames at each plot. All macroinvertebrate organisms (macroscopic organisms) in litter and mineral soil up to 25cm, were collected. Totally, 18 samples were collected. In these treatments, earthworm constituted the largest part of soil macrofauna. Earthworm abundance and biomass were highest in Acacia plantation whereas Arthropods did not show any significant differences. Since soil macrofauna was dominated with earthworm, its variations are in line with earthworm. The abundance and biomass of earthworm and soil macrofauna were negatively correlated with the C/N ratio. Lower earthworm abundance and biomass under Eucalyptus plantation could be as a result of its leaf phenolics or soil nitrogen limitation. Totally, it could be concluded that different tree species had various effects on soil macrofauna (especially earthworm) abundance and biomass. As Acacia species increased the soil macrofauna and improved soil fertility, it could be preferred species for plantation in this area.